Drill strings of pipe for oil and gas wells are assembled or disassembled vertically on a derrick one joint at a time, and are stored horizontally on pipe racks situated on the ground adjacent the rig. The work floor of the rig is typically elevated substantially above the pipe rack such that transferring sections of pipe to and from the work floor and the racks is necessary and requires careful handling of the heavy pipe to protect the workers and the pipe.
Conventional systems based on a boom having a pipe receiving trough in which pipe may be placed typically also include some way to eject sections of pipe out of such trough.
A variety of ejection mechanisms are known for removing pipe from a trough. For example U.S. Pat. No. 4,371,302 to Frias et al (‘302’) teaches a means for tilting an entire trough in a boom assembly that does not itself rise to the derrick work floor but merely feeds a second boom one end of which is pivotally coupled to the work floor. Disadvantageously, tilting an entire trough or boom requires significantly more power and compromises the potential rigidity of the boom more than is necessary when a short kicker member or section of trough is tilted to the same effect.
U.S. Pat. No. 3,143,221 to Blackmon (‘221’) teaches a pipe car pulled and released by a cable and having 2 sets of side-mounted wheels each set having a common axle and running in a channel in a fixed track, with a v-shaped carriage member that tilts to either side of the pipe car in a manner similar to the tilting car of U.S. Pat. No. 24,907 to Maydew (‘907’). Disadvantageously all known car designs run in a stationary track and require separate power and trigger assemblies.
U.S. Pat. No. 4,235,566 to Beeman (‘566’) teaches a dump arm pivotally connected to a boom and fastened to an hydraulic ram that is connected to the boom, such configuration disadvantageously adds weight and complexity to the boom.
Applicant's Canadian application CA 2224638 teaches a number of embodiments of a kicker together with a kicker rod. However, such design necessarily uses power and trigger assemblies that are separate from the boom.
The prior art in the oil-field service industry has concentrated on teaching variations on power driven tilting troughs and hydraulically powered kickers mounted on the boom or on the base and relying on a separate source of the power needed to cause ejection. None of the prior art, however, teaches an ejector that uses passive actuator members and is operable without a separate trigger and source of power to cause the ejecting motion.